Control system for electric motors.



M. HARTBNHEIM. CONTROL SYSTEM FOR ELECTRIC MOTORS. APPLICATION FILED JUNE 7, 1909.

947,329, Patented Jan.25, 1910.

2 SHEETS-SEEET 1.

INVENTOR 7 A TTORNEY Q I 'M HARTENHEIM. GQNTROL SYSTEM FOR ELECTRIC MOTORS.

APPLIQATION FILED JUNE 7, 1909.

Patented Jan. 25,

INVENTOR ATTORNEY an auxiliary exciting circuit in addition to UNITED STATES PATENT OFFICE.

MAX HARTENHEIM, OF HALE, ENGLAND. ASSIGNOB 'IO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CONTROL SYSTEM FOR ELECTRIC MOTORS,

To all whom it may concern: I Be it known that I, MAX Han'rnnnunr, a subject of the German Empire, and a resident, of Ashleigh, Park Road, Hale, Cheshire, England, have invented a new and useful Improvementin Control Systems for Electric Motors, of which the following is a specification.

This invention relates to control systems for electric motors and particularly to systems in which the speed and direction of rotation of the motor is controlled by varying the field of the generator which supplies in with energy. y

In systei'ns of the character above indicated, it is desirable to reduce the excitation ofthe generator and to increase the excitation of the motor when the load on the motor is increased inorder to prevent an abnormal increase in the power given out by the generator.

It hasalready been proposed to provide l l i 1 l l i l l i l l l l the ordinary exciting circuit of the motor and generator, the windings of which are so arranged on the motor field magnet as to assist the ordinary field magnet windings while on the generator field magnet, the auxiliary windings are arranged as to oppose the eticct of the ordinary field magnet windings. The exciter for the auxiliary field circuit has its field magnet so arranged that the excitation varies in accordance with the current supplied from the main gem. orator to the motor. necessitates two separate windings on the field magnets of both generator and motor, and it is the object of my invention to avoid the use of auxiliary windings'and also to reduce the size of the additional exciter.

According to my present invention, the field m agnet. windings of the generator and of the motor are arranged the one on the one side and the other on the side of the neutral wire of a three-wire circuit and the exciting generator is constructed as a three-wire ma chine, in a well known manner. In the neutral wire of the three-wire circuit, I connectthe armature ol the additional exciter. the field magnet of which is connected in par allcl with. a resistance in the main circuit of the generator and motor or is otherwise arranged so that the excitation shall vary with the current in the said circuit. Under these circumstances, it will bereadily seen that the l Specification ot' Letters Patent.

' Application filed June 7, 1909.

This arrangement Patented Jan. 25. 19M).

Serial No. 508.635.

tional exciter that is required in coni'iectio'n with the method heretofore proposed. 70

The invention is illustrated in the accompanying drawings, of which- Figure l is a diagran'luuitic view of a control system of the above character sin-- bodying the invention: Figs. 2, 3 and 4: are; 7 diagrammatic views illustrating modifications of a part otthc system of Fig. 1, Fig. 5 showing the same part of the system of Fig. l for the purpose of comparison.

Referring now to Fig. l. a direct; current generator 1 is driven by a threcpl iase induction motor 2 which is connected to a supply circuit 3 and is 1'n-ovidcd with a fly-wheel 4. The hrushes 5 of the generator 1 are con nected to the brushes 6 of a direct current motor 7 which operates an intermittent load. The field magnet. winding 8 of the generator 1 and the field magnet winding 9 of the mo tor 7 are connected in series across the brushes 10 of a tln'cewire cxciter 11 which is driven by a motor the third terminal 21 of the excitcr 11 being connected in series with the armature 13 of an additional exciter to the junction 15 of the field magnet windings 8 and 9. A reversing'switch 95 16 and a rheostat- 17 are also connected in series with the field magnet. winding 8. The lield magnet winding 18 of the additional exciter H: is connected. through a reversing; switch If). to the terminals of a resistance 20 which im'ludcd in one of the conductors connecting the brushes and 6 of the generator 1 and the motor 7, respectively.

The operation of the system is as follmvsz-Jlhe voltage generated by the additional cxciter l t which is connected in the third wire of the threewire exciter 11, causes an increase in the current traversing the field magnet winding 9 of the motor 7 and a decreas in tl'ie current traversing the field winding 8 of the generator 1 which is proportional to the load on the motor 7, since the excitation of this additional exciter is derived from the terminals of the resistance 20. By means of the reversing switch 16, a reversal of the direction of retation of the motor 7 may be elfectcd, the rheostat 17 providing a manual adjustment for the excitation of the generator 1. The reversing switch 19 is provided in order that the voltage generated by the additional exciter-14 may always cause an increase in the current traversing the field magnet winding 9 Whatever may be the direction of rotation of the motor 7. v The reversing switch 19 may, of course, be arranged to be operated by the movement of the lever which operates the reversing switch 16. The third wire 21 of the three-wire exciter 11 may be connected either directly to the middle point of the armature winding of the exciter,'as shown in Fig. 1, or it may be connected to an auxiliary set of brushes located in the neutral plane of the machine, as illustrated in Fig. 2.

As a further modification, the three-wire exciter may be provided with two armature windings and two commutators, as shown in Fig. 3, the brushes ot' dill'erent polarity on two commutators being connected together by the third wire. It is also possible to interchange the three-wire exciter and the ad ditional exciter, that is to say, to construct "the exciter as an ordinary direct current machine with two brushes and the additional exeiter as a three-wire machine, such an arrangement being illustrated in Fig. l. In this case, the auxiliary machine It is conneet'ed to the field magnet windings kt and 9 of the generator and motor, respectively, in such manner that each halt' ot' the armature winding 13 of the auxiliary machine is in series with one of these flcld magnet. windings, the armature 12 of the cxciter 11 being 'connected between the junction 15 of the field magnetwindings 8 and 9 and the third wire 21 of the auxiliary exciter 14.

The arrangement shown in Fig. -.t has the disadvantage that. tl auxiliary cxciter must be ot much greater capacity than with the arrangement. shown in Fig. l, as will be readily understood from a comparison of Figs. 4 and 5, Fig. showing the cxcitcr and the auxiliary excitcr connected as shown in Fig. 1. In both Figs. 1 and 5, the current traversing the field magnet winding 8 is indicated by the arrow 18 and the current traversing the field magnet winding 9 by the arrow 19*. By reference to Fig. 5, it will be seen that the armature 13 of the auxiliary exciter 14 need only be of suflicient capacity to carry the difierence between the currents 1t) and 18. In the arrangement shown in Fig. 4, however, the armature 13 of the auxiliary exciter 14 must be of sufficient capacity to carry the sum of the currents 18 and 19, since both of these currents pass through the auxiliary exciter on their way to the exciter 14.

I claim as my invention:

1. In a motor-control system, the combination with a generator and a motor having their armatures electrically connected together in series and their field magnet windings similarly connected together, of two auxiliary generators one of which is included in said field magnet circuit and is provided with a balancing conductor which is connected through the other to a point in the field magnet circuit which is located between the two windings.

2. 'In a motor-control system, the combination with a generator and a motor having their armature windings and their field magnet. windings connected together in separate circuits, of two auxiliary generators mechanically coupled together, one of which is included in said field magnet circuit and is provided with a balancing conductor which is connected. through the other generator, to a point. in the field magnet circuit. which is located between the two windings.

it. The combination with a main circuit, a main motor operatively connected to said circuit. a main generator driven by said motor and a controlled motor having its armature in series-with the armature of said main generator, of series-connected field magnet windings for said main generator and controlled motor, an auxiliary motor 0peratively connected to the main circuit and two auxiliary generators driven by said auxiliary motor. one of said generators being included in circuit of the field magnet windings of the main generator and the controlled motor and having a balancing conductor which is connected, through the other, to said field magnet winding circuit between the windings.

in test itnony whereof, I have hereunto subscribed my name this Hth day of Way, 1909.

MAX HARTENHEIM.

\Vil nesses:

NORMAN H. SHEARD, J AS. STEWART BROADFOOT. 

